#include<bits/stdc++.h>
using namespace std;
int main(){
  int n,g,s,b,q,x,c=0;
  cin>>n;
  for(int i=1;i<=n;i++){
  x=i;
  g=x%10;
  s=x/10%10;
  b=x/100%10;
  q=x/1000%10;
  if(x%5==0&&(g==5||s==5||b==5||q==5)) c++;
  }
cout<<c;
return 0;
}
 
	
	
 
/**************************************************************
	Problem: 1057
	User: wangyousi
	Language: C++
	Result: Accepted
	Time:25 ms
	Memory:2072 kb
****************************************************************/